Compton Observatory Science Report #172, Monday December 12, 1994 Chris Shrader, Compton Observatory Science Support Center Questions or comments can be sent to the CGRO SSC. Phone: 301/286-8434 e-mail: NSI_DECnet: GROSSC::SHRADER Internet: shrader@grossc.gsfc.nasa.gov Science Support Center News The schedule for the release of the Cycle-5 NRA and the due date for proposals is being modified resolve conflicts with the scheduled releases of the XTE and ROSAT NRAs. If we followed our original plan of an April 3, 1995 due date, proposals for all three missions would be due at the same time - not a pleasant prospect for proposal writers or review organizers! The exact due date for CGRO Cycle-5 proposals has not been finalized, but March 22, 1995 is most likely. Once the dates are finalized, the NRA and Appendices will be made available electronically at the CGRO-SSC. The BATSE CD rom, which contains data for gamma-ray bursts in the 2B catalog is being pressed at Goddard this week. It will be distributed at the forthcoming 185'th meeting of the American Astronomical Society. FYI, several CGRO-SSC computers have undergone name changes: old name new name -------------------- enemy --> cossc fiend --> grjuke villain --> cosmic (in all cases the internet extensions are ".gsfc.nasa.gov"). Please update your files/software to reflect this change. The original names are currently still supported but this will no the case after January 1,1995. Instrument Reports EGRET EGRET operations were normal this biweekly period. Delivery of data to the GRO SSC remains on schedule. Interaction with guest investigators continues at a good level. The deep survey of the Virgo region began on November 29, 1994; the results of this survey should add significantly to our knowledge of AGN's, including their time histories and luminosity distribution. There will be a series of talks at the Relativistic Astrophysics meeting in Munich next week, including a talk on EGRET highlights in a session of Highlights from the Compton Gamma Ray Observatory, a talk on pulsars, a paper on AGN's, and a talk on gamma-ray bursts. OSSE OSSE operations are normal. In viewing period 405.0 (29 Nov - 7 Dec), the Z-axis target was 3C 279 (PI team) and the X-axis target was the galactic center region, including GX1+4 in its current active state (PI team). In the Target of Opportunity viewing period 405.5 (7-13 Dec), the Z-axis target remains 3C 279 (PI team), while the X-axis target is the X-ray nova GRO J1655-40 (PI team) during an outburst. In data from the first 7 hours of this Target of Opportunity, the X-ray nova is clearly detected to at least 300 keV. The spectrum is, so far, consistent with a simple power law. Data from viewing periods 232 and 232.5 were delivered to the Compton GRO Science Support Center archive this week. The targets during these viewing periods were the galactic plane near (l,b) = (347,0), a portion of the Virgo Sky Survey region, Mrk 421, NGC 4388, and M87. The delivery of data products is now complete through the end of Phase 2 of the mission. COMPTEL The COMPTEL instrument is performing well and continues routine observations. An extensive report on "COMPTEL Observations of Galactic 26-Aluminum Emission" by R. Diehl et al. has recently been accepted for publication and will appear in Astronomy & Astrophysics. Preprints are currently being prepared for distribution. Also, a paper entitled "Diffuse Continuum Gamma Rays from the Galaxy observed by COMPTEL" by Strong et al. has appeared in A&A (1994) Vol 292 pp 82-91 (Dec 1 issue). It contains the full details of the analysis of the Galactic diffuse emission for Phase 1 data. postscript version is available from the author (aws@mpe-garching.mpg.de). The collaboration is investigating ways to make postscript versions of team publications available to interested parties. The COMPTEL Burst Rapid Response team continues to refine its processing procedures, to alert outside investigators of the positions of GRBs detected by COMPTEL. With the new automated data-processing procedures now in place, a GRB within the field of view of COMPTEL can routinely be located within approximately 16 minutes of burst occurrence (this includes the accumulation of 6 minutes of post-trigger COMPTEL data, plus 10 minutes of rapid data-processing, to produce a skymap of the burst field). BATSE The x-ray transient GRO J1655-40 is currently in outburst with variable intensity. Since Dec 3 the 20-100 keV flux has averaged 1.3 Crab. On Nov 28, the source reached nearly 2 Crab. The current outburst which has lasted nearly a month, is longer and more intense than the two other episodes detected in August and September. The following sources were detected by the BATSE pulsed source monitor in the past two weeks: Her X-1, Cen X-3, 4U 1626-67, 2S 1417-624, GX 1+4, Vela X-1, and GX 301-2. The outburst of 2S 1417-624 has now lasted 104 days. The x-ray binary GX 1+4 is still spinning up. Three BATSE Scientists, Drs. Fishman, Kouveliotou, and Paciesas, are currently attending IAU Colloquium 151,"Flares and Flashes: Views from the Ground & Space" in Sonneberg, Germany, where they will present papers. As of December 6th, BATSE has detected 1181 cosmic gamma-ray bursts out of a total of 3207 on-board triggers in 1323 days of operation. There have been 740 triggers due to solar flares with emission above 60 keV. Since the BATSE burst trigger criteria were changed on September 19th, there have been 11 triggers due to terrestrial gamma-ray flashes.